Analysis unit and system for assessment of hair condition

ABSTRACT

Some embodiments are directed to an analysis unit for assessment of hair condition, including a map processor configured to at least: obtain a first follicular map representing a first plurality of hair root positions in a first videodermoscopy image, obtain a second follicular map representing a second plurality of hair root positions in a second videodermoscopy image, determine a common skin area from the first follicular map and the second follicular map, relate hair root positions in the second follicular map to hair root positions of the first follicular map in the common skin area to determine a plurality of related hair root positions, and compare a change in condition of individual hair between the first and second videodermoscopy image to determine the analysis result suitable for assessment of hair condition.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patent ApplicantSer. No. 15/675,117 filed on Aug. 11, 2017, which claims benefit ofPolish Priority Patent Application P.420023 filed Dec. 29, 2016, theentire contents of each of which are incorporated herein by reference intheir entireties.

FIELD

The invention relates to an analysis unit for assessment of haircondition, a system for assessment of hair condition, a method forassessment of hair condition, and a computer program product.

BACKGROUND ART

Hair condition, in particular hair disorders, have traditionally beenassessed by clinical inspection and a number of invasive methodsincluding a pull-test, a trichogram obtained from extraction ofapproximately hundred hairs for microscopic inspection of their roots,and patomorphology which uses biopsy after extraction of skin tissue formicroscopic inspection.

In 2006, it was proposed by Ross, E K, Vincenzi, C I, and Tosti, A. thata dermoscope or videodermoscope, traditionally used for skin lesionobservations, may be used for diagnosing hair disorders. Since thentheir method, usually referred to as trichoscopy, has gained somepopularity due to its non-invasiveness. A number of studies have beencarried out to provide guidelines for disease diagnosis based on visual,qualitative inspection of the videodermosopy images by a traineddermatologist doctor. Visual trichoscopy has generally focused onsetting the initial diagnosis based on certain characteristic featuresobserved in the dermoscopy images of the scalp, such as broken hair,yellow dots, black dots, tulip hair, arborizing vessels, etc. Thisqualitative inspection of the videodermosopy images did not providetools to, for example, clearly distinguish between most commonconditions like to distinguish Androgenetic alopecia (AGA) from diffuseAlopecia areata (AA) and Telogen effluvium (TE), precisely measureadvancement of AGA, or to precisely measure therapy efficiency oncemedication is introduced.

The term trichoscopy may further be used to refer to a technique used inthe assessment of hair condition, examination of symptoms of hairdisorder, diagnosis of hair disorders, and monitoring hair treatmentefficiency. Trichoscopy uses a microscopic camera, a so-calledvideodermoscope to register high resolution images of hair and scalp orother skin. Such images may further be referred to as videodermoscopyimages. In known methods, the videodermoscopy images are subject tomanual or computer-assisted analysis to try to identify all hair shaftsand measure hair diameters. A statistical analysis of images registeredbefore and after the treatment allows to assess the response totreatment in terms of, for example, hair number or hair density, hairthickness and hair volume. In order to try to detect therapeutic effectsin the pre- and post-image comparison, a multiple micro tattoo markingis used to help to identify the same skin location and field of view,with the aim of positioning the videodermoscope at the same positionafter the treatment as before. Known methods suffer from variouslimitations. For example, it may be difficult or even impossible to drawany conclusions if the overall hair density change is statisticallyinsignificant. Also, currently used methods do not allow to ensure thatthe pre- and post-images represent really the same skin area. Further,with known methods, the precision of the analysis relies strongly onexactly the same positioning of the camera on the skin and the samefield of view.

Known trichoscopy techniques used in the assessment of hair condition,examination of symptoms of hair disorder, diagnosis of hair disordersand monitoring hair treatment efficiency thus still suffer from variouslimitations.

SUMMARY

A first aspect of the invention provides an analysis unit for assessmentof hair condition, the analysis unit comprising a map processor, the mapprocessor being arranged to at least obtain a first follicular maprepresenting a first plurality of hair root positions in a firstvideodermoscopy image, and analyse at least the first follicular map todetermine an analysis result suitable for assessment of hair condition.Assessment of hair condition may comprise supporting examination ofsymptoms of hair disorder, supporting examination of symptoms of skindisorder, supporting diagnosis of hair disorder, supporting diagnosis ofskin disorder, supporting examination of treatment, supportingexamination of a change in hair condition, or supporting examinationand/or evaluation of treatment efficiency. The analysis result suitablefor assessment of hair condition may relate to, consist of or comprise aparameter known and used in triochoscopy such as hair density. Theanalysis result suitable for assessment of hair condition may relate to,consist of or comprise any other analysis result for assessment haircondition, such as, for example, one of the analysis results describedwith reference to embodiments below, for example being indicative ofAGA. The analysis unit may be arranged to support diagnosis of hairdisorder. The analysis unit may additionally or alternatively bearranged to support examination and/or evaluation of treatmentefficiency. The analysis unit may be used in trichoscopy to assess haircondition. Using the first follicular map representing the firstplurality of hair root positions as an alternative of using acorresponding first videodermoscopy image, or in addition to using thecorresponding first videodermoscopy image, may provide an analysisresult that is better suitable for assessment of hair conditionaccording to known methods. The analysis result may, for example,comprise a known type of analysis result, such as hair density, that ismore accurately determined than at least some known methods. Theanalysis result may, additionally or alternatively, comprise a new typeof result that is better suitable than known types as, for example, aresult indicative of a degree of AGA. Examples are described below withreference to various embodiments. The analysis unit may be arranged toanalyse a plurality of follicular maps, the plurality of follicular mapscomprising the first follicular map, to determine an analysis resultsuitable for assessment of hair condition. The analysis unit may bearranged to analyse at least the first follicular map and acorresponding first videodermoscopy image, to determine an analysisresult suitable for assessment of hair condition. The variousembodiments described below may be used autonomously or in combinationof one or more embodiments. The embodiments described may overcome,reduce or alleviate various limitations of known trichoscopy techniques.The specific limitation or limitations that are overcome, reduced oralleviated by a specific embodiment may be different for the differentembodiments and any combinations thereof.

In an embodiment, the analysis unit further comprises an imageprocessor, the image processor being arranged to perform an imageprocessing algorithm on a first videodermoscopy image to generate thefirst follicular map representing the first plurality of hair rootpositions in the first videodermoscopy image, and the map processorbeing arranged to obtain the first follicular map from the imageprocessor.

In an embodiment, the image processor is arranged to, as part ofobtaining the first follicular map, cooperate with a map modificationunit, the map modification unit being arranged to present the firstfollicular map as obtained from the performing of the image processingalgorithm on the first videodermoscopy image to a human assistant, andallow the human assistant to review the first follicular map and tomodify the first follicular map such as to, at least, add and/or removeone or more hair root positions from the first follicular map.

In an embodiment, the map processor is arranged to, as part of analysingat least the first follicular map to determine the analysis result,perform a statistical analysis of hair root distances between hair rootspositions of the first plurality of hair root positions.

In an embodiment, the map processor is arranged to, as part ofperforming the statistical analysis of hair root distances between hairroot positions, determine a hair root distance distribution, anddetermine at least a first and a second relative contribution to thehair root distance distribution of at least a first and a seconddistribution component function.

In an embodiment, the relative contribution of the first distributioncomponent function is an indication for a degree of a hair disorder of afirst type. For example, the relative contribution of the firstdistribution component function is an indication for a degree of AGA.

In an embodiment, the map processor is further arranged to at leastobtain a second follicular map representing a second plurality of hairroot positions in a second videodermoscopy image, and determine a commonskin area from the first follicular map and the second follicular map.The map processor may further be arranged to use the common skin area inanalysing at least the first follicular map to determine the analysisresult suitable for assessment of hair condition. The map processor maybe arranged to use the common skin area in analysing at least the firstand the second follicular map to determine the analysis result suitablefor assessment of hair condition. For example, comparing the common skinarea of a first follicular map obtained from a first videodermoscopyimage recorded at a first moment in time with the common skin area ofthe second follicular map obtained from a second videodermoscopy imagerecorded at a second, later, moment in time may provide an analysisresult that is better suitable for assessment of hair condition thanknown methods, such as for assessment of a change in hair conditionbetween the first moment and the second moment, for example as result ofa treatment. For example, the analysis result may comprise a change inhair density and/or a change in number of hair and/or identification ofappeared and disappeared hair, which may be more accurately obtainedusing the common skin area than from a mere comparison of the first andsecond videodermoscopy images or the corresponding hair densitiesdetermined therefrom. Other examples are described below with referenceto various embodiments.

In an embodiment, the map processor is further arranged to obtain asequence of second follicular maps, each second follicular maprepresenting a second plurality of hair root positions in an associatedsecond videodermoscopy image of a corresponding sequence of differentsecond videodermoscopy images, and determine a common skin area from thefirst follicular map and at least one of the second follicular maps ofthe sequence of second follicular maps. Thus, the sequence of secondvideodermoscopy images may be acquired from the person's skin withoutthe need to know the exact location and without the need for additionalreference symbols such as, e.g., micro-tattoos: the first follicular mapeffectively acts as the location reference, and could be considered tofunction as a virtual tattoo. With this embodiment, the system may notjust be arranged for determining an analysis result suitable forassessment of hair condition, but the system may additionally oralternatively be arranged for determining an analysis result suitablefor assessment of skin condition. Herein, the follicular maps may beused to determine a corresponding skin area when a skin condition, andparticularly a change in skin condition, is to be assessed. The skincondition may e.g. relate to detecting, measuring or monitoring skincolor, skin color variation, presence and growth of birthmarks, naevus,scars, skin burn, skin recovery, and their development over time.

In an embodiment, the image processor is further arranged to perform animage processing algorithm on a second videodermoscopy image to generatethe second follicular map representing the second plurality of hair rootpositions in the second videodermoscopy image, and the map processor isarranged to obtain the second follicular map from the image processor.

In an embodiment, the map processor comprises a matching unit, thematching unit being arranged to at least relate hair root positions inthe second follicular map to hair root positions of the first follicularmap in the common skin area to determine a plurality of related hairroot positions, each related hair root position of a hair root in thesecond follicular map being related to a hair root position in the firstfollicular map of the same hair root. A related hair root position of ahair root in the second follicular map may hereby be related to a hairroot position in the first follicular map of the same hair rootrepresenting presumably the same hair follicle in the second and firstvideodermoscopy images. The map processor may further be arranged tocompare a change in condition of individual hair between the first andsecond videodermoscopy image to determine the analysis result suitablefor assessment of hair condition.

In an embodiment, the matching unit is arranged to initialize atransformation function, and to iteratively adapt the transformationfunction, the iterative adaption comprising applying the transformationfunction to the first plurality of hair root positions of the firstfollicular map to obtain a first plurality of transformed hair rootpositions, relating the first plurality of transformed hair rootpositions to the second plurality of hair root positions of the secondfollicular map, determining relative distances between transformed hairroot positions of the first plurality of transformed hair root positionsand the related hair root positions of the second plurality of hair rootpositions to obtain a correspondence metric, and adapting thetransformation function to minimize the correspondence metric.

In an embodiment, the matching unit is arranged to, as part ofiteratively adapting the transformation function, further use at leastone parameter of hair associated with the transformed hair rootpositions and hair associated with the related hair root positions toobtain the correspondence metric, the at least one parameter comprisingat least one parameter from a group consisting of hair shaft diameter,hair length, hair growth, hair color.

In an embodiment, the matching unit is arranged to, as part ofinitializing the transformation function, detect positions of a firstplurality of reference symbols on the skin in the first videodermoscopyimage, detect positions of a second plurality of reference symbols onthe skin in the second videodermoscopy image, and initialize thetransformation function to reflect a transformation from the positionsof a first plurality of reference symbols to the positions of a secondplurality of reference symbols. In an embodiment, the map processor isfurther arranged to at least analyse differences between at least thecommon skin area in the first follicular map and the common skin area inthe second follicular map to determine the analysis result suitable forassessment of hair condition.

In an embodiment, the map processor is further arranged to, indetermining the analysis result, identify an appearing of new hairshafts in the common skin area in the second follicular map compared tothe common skin area in the first follicular map.

In an embodiment, the map processor is further arranged to, indetermining the analysis result, identify a disappearing of hair fromthe common skin area in the second follicular map compared to the commonskin area in the first follicular map.

In an embodiment, the map processor is further arranged to at leastanalyse differences between at least the common skin area in the firstvideodermoscopy image and the common skin area in the secondvideodermoscopy image to determine the analysis result suitable forassessment of hair condition.

In an embodiment, the map processor is further arranged to, in analysingdifferences between at least the common skin area in the firstvideodermoscopy image and the common skin area in the secondvideodermoscopy image, determine differences between at least oneparameters of a group of parameters consisting of average hair diameter,hair diameter distribution, average hair length, hair lengthdistribution, hair colors, hair color distribution, and/or at least onehair density.

The hair condition may thus comprise or relate to hair length or changeof hair length. Comparing a change in condition may comprise orcorrespond to comparing lengths of individual hairs in the first andsecond videodermoscopy images to determine a length increase, usuallygrowth, or a length reduction, e.g. from shaving or cutting.

In an embodiment, the map processor is further arranged to, in analysingdifferences between at least the common skin area in the firstvideodermoscopy image and the common skin area in the secondvideodermoscopy image, compare lengths of individual hair between thefirst videodermoscopy image captured from a part of a skin, such as partof a human scalp, before shaving and lengths of the same individual hairin a second videodermoscopy image captured from the same part aftershaving as part of an examination of shaving performance on haircondition, in particular hair length. Hereby, an analysis resultsuitable for the assessment of hair condition may be obtained which isindicative for the shaving performance.

In an embodiment, the map processor is further arranged to, in analysingdifferences between at least the common skin area in the firstvideodermoscopy image and the common skin area in the secondvideodermoscopy image, compare lengths of individual hairs between afirst videodermoscopy image captured from a part of a skin, such as partof a human scalp, immediately after shaving and a second videodermoscopyimage captured from the same part one or more days after shaving, and tocalculate estimates of the lengths of individual hairs immediately aftershaving from the change of lengths. Hereby, it becomes possible to alsoassess the quality of shaving, such as of close shaving that uses arazor blade arranged to pull hair out and cut the hair effectively belowskin surface: the estimates may then provide negative lengths ofindividual hairs as a result of the shaving. The analysis resultsuitable for assessment of hair condition may thus be a set of lengths,which may include negative lengths, of individual hairs reflecting thehair condition immediately after shaving, or one or more statisticalparameters measured on the set of negative lengths of individual hairreflecting statistical performance indicators of the hair conditionafter shaving, such as an average (possible negative) length. The partof a skin may, e.g., be a part of a human skin such as a part of a humanscalp, face, or another body part.

In an embodiment, the map processor is further arranged to, in analysingdifferences between at least the common skin area in the firstvideodermoscopy image and the common skin area in the secondvideodermoscopy image, compare presence and/or diameters and/or lengthsof individual hair between the first videodermoscopy image captured froma part of a skin before epilation and presence and/or diameters and/orlengths of the same individual hair in a second videodermoscopy imagecaptured from the same part after epilation as part of an examination ofepilation performance on hair condition, in particular hair extraction,hair diameter and hair length. Hereby, an analysis result suitable forthe assessment of hair condition may be obtained which is indicative forthe epilation performance. The assessment of epilation builds in part onthe recognition that the available techniques for epilation, such asmechanical, electrocoagulation and laser epilation, aim at hurting thehair follicle without too much skin damage: epilation will thus inpractice never lead to a 100% extraction of all hair from the hairfollicles. Further, the inventors recognized that hair cycling causes acertain fraction X % of hair follicles to be in the telogen/exogen phasethus to be “empty”. As a result, after one depilation session there isalways some hair regrowth due to follicles that got hurt but notdestroyed—these hairs will be thinner and grow slower- and due to theremaining X % of follicles that were not detected and not affected atall. This embodiment provides estimates of the positions of hairfollicles and the correspondence between hair follicle locations betweenthe first and second follicular maps, which allows to evaluate theremaining hair and to tell one effect from another.

In an embodiment, the map processor is further arranged to, in analysingdifferences between at least the common skin area in the firstvideodermoscopy image and the common skin area in the secondvideodermoscopy image, compare presence and/or diameters and/or lengthsof individual hair between a first videodermoscopy image captured from apart of a skin immediately or shortly after epilation and a secondvideodermoscopy image captured from the same part one or more days afterepilation, and to calculate estimates of the quality of epilation suchas percentage of successful epilation and/or diameter and/or lengths ofindividual hair immediately after epilation from the change of diametersand/or lengths. Hereby, it becomes possible to also assess the qualityof epilation, including the effect of pulling hair out and the damage tothe hair follicles. The latter result in some hair regrowth due tofollicles that got hurt but not destroyed—these hair will be thinner andgrow slower. The analysis result suitable for assessment of haircondition may thus comprise a set of quantitative measures of efficiencyof epilation, a set of diameters, a set of lengths of individual hairsreflecting the hair condition immediately after epilation, one or morestatistical parameters measured on the regrowth of individual hair,and/or an indicator indicative for the damage to hair follicles derivedfrom a statistical analysis of increase in diameters and lengths ofindividual hairs.

In an embodiment, the analysis unit comprises a zero-loss processor, thezero-loss processor comprising an input image processor, a matchingunit, and a follicular map combiner and/or an input image combiner, thezero-loss processor being arranged to receive a plurality of firstvideodermoscopy input images, the input image processor being arrangedto perform an image processing algorithm on each of the firstvideodermoscopy input images of the plurality of first videodermoscopyinput images to generate a plurality of first follicular maps, eachfirst follicular map representing a first plurality of hair rootpositions in the corresponding first videodermoscopy input image, thematching unit being arranged to at least relate hair root positions in asecond map of the plurality of first follicular maps to hair rootpositions of a first map in at least a common skin area of the first mapand the second map to determine a plurality of related hair rootpositions, the follicular map combiner being arranged to determine acombined first follicular map from the plurality of first follicularmaps, the input image combiner being arranged to determine a combinedinput image from plurality of first videodermoscopy input images usingthe plurality of first follicular maps. The plurality of firstvideodermoscopy input images may have been captured as a sequence ofvideodermoscopy images while rearranging the camera used for capturingthe videodermoscopy images and/or the hair in between successive images.The plurality of first videodermoscopy input images may e.g. have beencaptured as a sequence of videodermoscopy images taken shortly aftereach other, such as at intervals in a range of 10 ms to 10 minutes, suchas at intervals in a range of 10 ms to 50 ms, 0.5 sec to 30 sec, 1 to 5minutes, or any other suitable interval. The plurality of firstvideodermoscopy input images may e.g. have been captured using a digitalstill camera to provide a sequence of still images as the sequence ofvideodermoscopy images. The plurality of first videodermoscopy inputimages may e.g. have been captured using a video camera to provide asequence of video frames as the sequence of videodermoscopy images. Thesequence of video frames may for example have been captured at a framerate in a range of 10 to 100 Hz, such as at a frame rate of 16, 25, 50,60, 75 or 100 Hz, or any other suitable frame rate. The sequence ofvideodermoscopy images may correspond to a series of successive videoframes. The sequence of videodermoscopy images may correspond to asubsampled series of video frames, such as every second, every third,every fifth or every tenth video frame of a series of successive videoframes, or any other suitable subsampling rate. The plurality of firstvideodermoscopy input images may e.g. have been captured whilereorganizing the hair, such as by combing the hair, parting the hair,wetting the hair or any other suitable manner in between successivevideodermoscopy images. The plurality of first videodermoscopy inputimages may e.g. have been captured while shifting or rotating the camerain between successive videodermoscopy images, or varying the imagingdistance or magnification.

In an embodiment, the zero-loss processor is arranged to output thecombined first follicular map to the image processor, for use as thefirst or second follicular map in any one of the embodiments describedabove.

In an embodiment, the zero-loss processor is arranged to output thecombined input image to the image processor for use as the first orsecond videodermoscopy image in any one of the embodiments describedabove.

A second aspect of the invention provides a system for assessment ofhair condition, the system comprising an upload unit, an analysis unitaccording to any one of the preceding embodiments, and a presentationunit, the upload unit being arranged to receive one or morevideodermoscopy images, the one or more videodermoscopy imagescomprising at least the first videodermoscopy image and to upload theone or more videodermoscopy images to the analysis unit, the analysisunit being arranged to receive the one or more videodermoscopy imagesfrom the upload unit and to obtain a videodermoscopic analysis resultfrom the one or more videodermoscopy images, the videodermoscopicanalysis result comprising the analysis result suitable for assessmentof hair condition and/or an examination result derived from the analysisresult, and the presentation unit being arranged to receive thevideodermoscopic analysis result from the analysis unit and to presentat least part of the analysis result to a user.

In an embodiment, the system further comprising a result check unit, theresult check unit being arranged to receive the videodermoscopicanalysis result from the analysis unit, review the videodermoscopicanalysis result and to modify the videodermoscopic analysis result,provide the videodermoscopic analysis result as modified to thepresentation unit to allow the presentation unit to present at leastpart of the videodermoscopic analysis result as modified to the user.

In an embodiment, the upload unit is connected to the analysis unit viaa communication network.

In an embodiment, the presentation unit is connected to the analysisunit via a communication network.

In an embodiment, the system further comprises a user terminal, the userterminal comprising the upload unit and the presentation unit, the userterminal being connected to the analysis unit via a communicationnetwork.

A third aspect of the invention provides a method for assessment of haircondition, the method comprising obtaining a first follicular maprepresenting a first plurality of hair root positions in a firstvideodermoscopy image, and analysing at least the first follicular mapto determine an analysis result suitable for assessment of haircondition.

In an embodiment, the method further comprises performing an imageprocessing algorithm on a first videodermoscopy image to obtain thefirst follicular map representing the first plurality of hair rootpositions in the first videodermoscopy image.

In an embodiment, the method further comprises obtaining a secondfollicular map representing a second plurality of hair root positions ina second videodermoscopy image, and determining a common skin area fromthe first follicular map and the second follicular map.

In an embodiment, the method further comprises performing an imageprocessing algorithm on a second videodermoscopy image to obtain thesecond follicular map representing the second plurality of hair rootpositions in the second videodermoscopy image.

In an embodiment, the method comprises obtaining a sequence of secondfollicular maps, each second follicular map representing a secondplurality of hair root positions in an associated second videodermoscopyimage of a corresponding sequence of second videodermoscopy images, anddetermining a common skin area from the first follicular map and atleast one of the second follicular maps of the sequence of secondfollicular maps.

In an embodiment, the method comprises, in analysing differences betweenat least the common skin area in the first videodermoscopy image and thecommon skin area in the second videodermoscopy image, comparing lengthsof individual hair between the first videodermoscopy image captured froma part of a human scalp—or another part of a skin—before shaving andlengths of the same individual hair in a second videodermoscopy imagecaptured from the same part after shaving as part of an examination ofshaving performance on hair condition, in particular hair length.

In an embodiment, the method comprises, in analysing differences betweenat least the common skin area in the first videodermoscopy image and thecommon skin area in the second videodermoscopy image, comparing lengthsof individual hair between a first videodermoscopy image captured from apart of a human scalp—or another part of a skin—shortly after shavingand a second videodermoscopy image captured from the same part one ormore days after shaving, and calculating estimates of the lengths ofindividual hair immediately after shaving from the change of lengths.

In an embodiment, the method comprises receiving a plurality of firstvideodermoscopy input images, performing an image processing algorithmon each of the first videodermoscopy input images of the plurality offirst videodermoscopy input images to generate a plurality of firstfollicular maps, each first follicular map representing a firstplurality of hair root positions in the corresponding firstvideodermoscopy input image, relating hair root positions in a secondmap of the plurality of first follicular maps to hair root positions ofa first map in at least a common skin area of the first map and thesecond map to determine a plurality of related hair root positions, anddetermining a combined first follicular map from the plurality of firstfollicular maps and/or determining a combined input image from pluralityof first videodermoscopy input images using the plurality of firstfollicular maps.

In a further embodiment, the method comprises capturing a sequence ofvideodermoscopy images while rearranging the camera and/or the hair inbetween successive images. In an embodiment, the plurality of firstvideodermoscopy input images is captured as a sequence ofvideodermoscopy images taken shortly after each other, such as atintervals between 0.1 second and 10 minutes, such as at intervalsbetween 1 and 5 minutes. In an embodiment, the plurality of firstvideodermoscopy input images is captured using a digital still camera toprovide a sequence of still images as the sequence of videodermoscopyimages. In an embodiment, the plurality of first videodermoscopy inputimages is captured using a video camera to provide a sequence of videoframes as the sequence of videodermoscopy images. In an embodiment, theplurality of first videodermoscopy input images is been captured whilereorganizing the hair, such as by combing the hair, parting the hair,wetting the hair or any other suitable manner in between successivevideodermoscopy images. In an embodiment, the plurality of firstvideodermoscopy input images is captured while shifting or rotating thecamera in between successive videodermoscopy images, or varying theimaging distance or magnification.

In an embodiment, the method comprises uploading one or morevideodermoscopy images to an analysis unit via a communication network,for letting the analysis unit perform the method according to any one ofthe embodiments above, and receiving the videodermoscopic analysisresult from the analysis via the communication network.

In an embodiment, the method further comprises receiving one or morevideodermoscopy images by an upload unit, uploading the one or morevideodermoscopy images from the upload unit to an analysis unit via acommunication network, for letting the analysis unit perform the methodaccording to an embodiment, and presenting at least part of thevideodermoscopic analysis result to a user.

A fourth aspect of the invention provides a computer program productcomprising a computer program comprising instructions arranged to, whenexecuted by a computer, execute at least part of the method of any oneof the embodiments.

Aspects, embodiments and elements of the invention may be described byone or more of the following clauses. Further aspects, embodiments andelements may be derived from the rest of the application, such as fromthe rest of the summary, the brief description, the detailed descriptionand the claims as filed. Further aspects, embodiments and elements maybe derived from combining aspects, embodiments, elements and parts ofaspects, embodiments, elements and parts.

Clause 1. An analysis unit for assessment of hair condition, theanalysis unit comprising a map processor, the map processor beingarranged to at least:

-   -   obtain a first follicular map representing a first plurality of        hair root positions in a first videodermoscopy image, and    -   analyse at least the first follicular map to determine an        analysis result suitable for assessment of hair condition.

Clause 2. The analysis unit according to clause 1, the analysis unitfurther comprising an image processor, the image processor beingarranged to perform an image processing algorithm on a firstvideodermoscopy image to generate the first follicular map representingthe first plurality of hair root positions in the first videodermoscopyimage, and the map processor being arranged to obtain the firstfollicular map from the image processor.

Clause 3. The analysis unit according to clause 2, the image processorbeing arranged to, as part of obtaining the first follicular map,cooperate with a map modification unit, the map modification unit beingarranged to:

-   -   present the first follicular map as obtained from the performing        of the image processing algorithm on the first videodermoscopy        image to a human assistant, and    -   allow the human assistant to review the first follicular map and        to modify the first follicular map such as to, at least, add        and/or remove one or more hair root positions from the first        follicular map.

Clause 4. The analysis unit according to clause 1, the map processorbeing arranged to, as part of analysing at least the first follicularmap to determine the analysis result, perform a statistical analysis ofhair root distances between hair roots positions of the first pluralityof hair root positions.

Clause 5. The analysis unit according to clause 4, the map processorbeing arranged to, as part of performing the statistical analysis ofhair root distances between hair root positions:

-   -   determine a hair root distance distribution, and    -   determine at least a first and a second relative contribution to        the hair root distance distribution of at least a first and a        second distribution component function.

Clause 6. The analysis unit according to clause 5, the relativecontribution of the first distribution component function being anindication for a degree of a hair disorder of a first type.

Clause 7. The analysis unit according to any one of clauses 1-3, the mapprocessor being further arranged to at least:

-   -   obtain a second follicular map representing a second plurality        of hair root positions in a second videodermoscopy image, and    -   determine a common skin area from the first follicular map and        the second follicular map.

Clause 8. The analysis unit according to clause 7, the image processorbeing further arranged to perform an image processing algorithm on asecond videodermoscopy image to generate the second follicular maprepresenting the second plurality of hair root positions in the secondvideodermoscopy image, and

the map processor being arranged to obtain the second follicular mapfrom the image processor.

Clause 9. The analysis unit according to clause 7 or 8, the mapprocessor comprising a matching unit, the matching unit being arrangedto at least:

-   -   relate hair root positions in the second follicular map to hair        root positions of the first follicular map in the common skin        area to determine a plurality of related hair root positions,        each related hair root position of a hair root in the second        follicular map being related to a hair root position in the        first follicular map of the same hair root.

Clause 9A. An analysis unit for assessment of hair condition, theanalysis unit comprising a map processor, the map processor beingarranged to at least:

-   -   obtain a first follicular map representing a first plurality of        hair root positions in a first videodermoscopy image,    -   obtain a second follicular map representing a second plurality        of hair root positions in a second videodermoscopy image,    -   determine a common skin area from the first follicular map and        the second follicular map,    -   relate hair root positions in the second follicular map to hair        root positions of the first follicular map in the common skin        area to determine a plurality of related hair root positions,        each related hair root position of a hair root in the second        follicular map being related to a hair root position in the        first follicular map of the same hair root, and    -   compare a change in condition of individual hair between the        first and second videodermoscopy image to determine the analysis        result suitable for assessment of hair condition.

Clause 9B. The analysis unit according to clause 9A, the analysis unitfurther comprising an image processor,

the image processor being arranged to perform an image processingalgorithm on a first videodermoscopy image to generate the firstfollicular map representing the first plurality of hair root positionsin the first videodermoscopy image, and

the map processor being arranged to obtain the first follicular map fromthe image processor.

Clause 9C. The analysis unit according to clause 9B, the image processorfurther being arranged to perform the image processing algorithm on asecond videodermoscopy image to generate the second follicular maprepresenting the second plurality of hair root positions in the secondvideodermoscopy image, and

the map processor being arranged to obtain the second follicular mapfrom the image processor.

Clause 10. The analysis unit according to any one of clauses 7-9, themap processor being further arranged to at least analyse differencesbetween the common skin area in the first follicular map and the commonskin area in the second follicular map to determine the analysis resultsuitable for assessment of hair condition.

Clause 11. The analysis unit according to clause 10, the map processorbeing further arranged to, in determining the analysis result:

-   -   identify an appearing of new hair roots in the common skin area        in the second follicular map compared to the common skin area in        the first follicular map, and/or    -   identify a disappearing of hair roots from the common skin area        in the second follicular map compared to the common skin area in        the first follicular map.

Clause 12. The analysis unit according to any one of clauses 7-11, themap processor being further arranged to at least analyse differencesbetween at least the common skin area in the first videodermoscopy imageand the common skin area in the second videodermoscopy image todetermine the analysis result suitable for assessment of hair condition.

Clause 13. The analysis unit according to clause 12, the map processorbeing further arranged to, in analyse differences between at least thecommon skin area in the first videodermoscopy image and the common skinarea in the second videodermoscopy image, determine differences betweenat least one parameters of a group of parameters consisting of averagehair diameter, hair diameter distribution, average hair length, hairlength distribution, hair colors, hair color distribution, and/or atleast one hair density.

Clause 13A. The analysis unit according to any one of the precedingclauses, the analysis unit further comprising a zero-loss processor, thezero-loss processor being arranged to:

-   -   receive a plurality of first videodermoscopy input images        captured as a sequence of videodermoscopy images,    -   perform an image processing algorithm on each of the first        videodermoscopy input images of the plurality of first        videodermoscopy input images to generate a plurality of first        follicular maps, each first follicular map representing a first        plurality of hair root positions in the corresponding first        videodermoscopy input image,    -   relate hair root positions in a second map of the plurality of        first follicular maps to hair root positions of a first map in        at least a common skin area of the first map and the second map        to determine a plurality of related hair root positions,    -   determine a combined first follicular map from the plurality of        first follicular maps.

Clause 13B. The analysis unit according to clause 13A, the zero-lossprocessor being arranged to output the combined first follicular map tothe image processor for use as the first or second follicular map.

Clause 13C. The analysis unit according to clause 13A or 13B, thezero-loss processor being arranged to output the combined input image tothe image processor for use as the first or second videodermoscopyimage.

Clause 14. A system for assessment of hair condition, the systemcomprising:

-   -   an upload unit,    -   an analysis unit according to any one of the preceding clauses,        and    -   a presentation unit,    -   the upload unit being arranged to receive one or more        videodermoscopy images, the one or more videodermoscopy images        comprising at least the first videodermoscopy image and to        upload the one or more videodermoscopy images to the analysis        unit,    -   the analysis unit being arranged to receive the one or more        videodermoscopy images from the upload unit and to obtain a        videodermoscopic analysis result from the one or more        videodermoscopy images, the videodermoscopic analysis result        comprising at least one of:        -   the analysis result suitable for assessment of hair            condition, and        -   an examination result derived from at least one of the            analysis result suitable for assessment of hair condition,            and    -   the presentation unit being arranged to receive the        videodermoscopic analysis result from the analysis unit and to        present at least part of the analysis result to a user.

Clause 15. The system according to clause 14, the system furthercomprising a result check unit, the result check unit being arranged to:

-   -   receive the videodermoscopic analysis result from the analysis        unit,    -   review the videodermoscopic analysis result and to modify the        videodermoscopic analysis result, and    -   provide the videodermoscopic analysis result as modified to the        presentation unit to allow the presentation unit to present at        least part of the videodermoscopic analysis result as modified        to the user.

Clause 16. The system according to any one of clauses 14-15, the uploadunit and//or the presentation unit being connected to the analysis unitvia a communication network.

Clause 17. A method for assessment of hair condition, the methodcomprising:

-   -   obtaining a first follicular map representing a first plurality        of hair root positions in a first videodermoscopy image, and    -   analysing at least the first follicular map to determine an        analysis result suitable for assessment of hair condition.

Clause 18. The method of clause 17, the method further comprisingperforming an image processing algorithm on a first videodermoscopyimage to obtain the first follicular map representing the firstplurality of hair root positions in the first videodermoscopy image.

Clause 19. The method of clause 17 or 18, the method further comprising:

-   -   obtaining a second follicular map representing a second        plurality of hair root positions in a second videodermoscopy        image, and    -   determining a common skin area from the first follicular map and        the second follicular map.

Clause 19A. A method for assessment of hair condition, the methodcomprising:

-   -   obtaining a first follicular map representing a first plurality        of hair root positions in a first videodermoscopy image,    -   obtaining a second follicular map representing a second        plurality of hair root positions in a second videodermoscopy        image,    -   determining a common skin area from the first follicular map and        the second follicular map,    -   relating hair root positions in the second follicular map to        hair root positions of the first follicular map in the common        skin area to determine a plurality of related hair root        positions, each related hair root position of a hair root in the        second follicular map being related to a hair root position in        the first follicular map of the same hair root; and    -   comparing a change in condition of individual hair between the        first and second videodermoscopy image to determine the analysis        result suitable for assessment of hair condition.

Clause 20. The method of clause 19 or 19A, the method further comprisingperforming an image processing algorithm on a second videodermoscopyimage to obtain the second follicular map representing the secondplurality of hair root positions in the second videodermoscopy image.

Clause 21. A computer program product comprising a computer programcomprising instructions arranged to, when executed by a computer,execute at least part of the method of any one of clauses 17-20.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention are apparent from and will beelucidated with reference to the embodiments described hereinafter. Inthe drawings,

FIG. 1 shows an analysis unit for assessment of hair condition accordingto an embodiment, FIG. 2 shows an analysis unit for assessment of haircondition according to a further embodiment,

FIG. 3a and FIG. 3b schematically shows distributions measured infollicular maps of a first and a second person respectively,

FIG. 4 shows an analysis unit for assessment of hair condition accordingto another embodiment,

FIG. 5 schematically shows a first and second follicular map and thecommon skin area,

FIG. 6 schematically shows an analysis unit according to anotherembodiment,

FIG. 7 schematically shows a use of a videodermoscopy camera accordingto an embodiment,

FIG. 8 schematically shows videodermoscopy images and follicular maps toillustrate the embodiment of FIG. 6,

FIG. 9 schematically shows an analysis unit for assessment of haircondition according to again another embodiment,

FIG. 10 schematically shows an analysis unit for assessment of haircondition according to again another embodiment,

FIG. 11 schematically shows a zero-loss processor according to anembodiment, FIG. 12 schematically shows videodermoscopy images andfollicular maps to illustrate the zero-loss processor of FIG. 11,

FIG. 13 schematically shows a system SYS for assessment of haircondition,

FIG. 14-FIG. 16 schematically show methods for assessment of haircondition according to embodiments,

FIG. 17 schematically shows a method of zero-loss videodermoscopic imageprocessing according to an embodiment, and

FIG. 18 shows a computer readable medium comprising a computer programproduct.

It should be noted that items which have the same reference numbers indifferent Figures, have the same or corresponding structural featuresand the same or corresponding functions, or are the same orcorresponding signals. Where the function and/or structure of such anitem has been explained, there is no necessity for repeated explanationthereof in the detailed description.

DETAILED DESCRIPTION

FIG. 1 shows an analysis unit ANA for assessment of hair conditionaccording to an embodiment. The analysis unit ANA comprises a mapprocessor MPP. The map processor is arranged to at least obtain a firstfollicular map FM1 representing a first plurality of hair root positionsin a first videodermoscopy image. The map processor is further arrangedto analyse at least the first follicular map FM1 to determine ananalysis result ANR1 suitable for assessment of hair condition.

The map processor MPP may be arranged to obtain the first follicular mapFM1 from a storage. The map processor MPP may be arranged to obtain thefirst follicular map FM1 from receiving the first follicular map FM1over a communication channel, such as from a communication network. Themap processor may obtain the first follicular map from a storage, suchas from a patient database wherein the first follicular map is stored.The map processor may alternatively obtain the first follicular map froman image processor that is arranged to generate the first follicular mapfrom a first videodermoscopy image.

Examination of hair condition may relate to diagnosis of hair disorders.Examination of hair condition may additionally or alternatively relateto identification and/or measurement of an advancement of hair disorder,measurement of a result of a treatment of a hair disorder, measurementof an effect and/or effectiveness of a medical treatment, or measurementof an effect and/or effectiveness of a cosmetic treatment.

The analysis result may, e.g., comprise an average hair root density, anaverage distance between hair roots, statistical parameters representinga statistics of distances between hair roots, or another parameterderivable from hair root positions.

FIG. 2 shows a further embodiment of an analysis unit ANA′ forassessment of hair condition according to an embodiment. The analysisunit ANA′ comprises an image processor IMP and a map processor MPP. Theimage processor IMP is arranged to perform an image processing algorithmon a first videodermoscopy image IM1 to generate a first follicular mapFM1 representing a first plurality of hair root positions in the firstvideodermoscopy image IM1. The map processor MPP is arranged to obtainthe first follicular map from the image processor IMP. As in theembodiment shown in FIG. 1, the map processor is further arranged toanalyse at least the first follicular map FM1 to determine an analysisresult ANR1 suitable for assessment of hair condition.

The map processor may be connected to the image processor and arrangedto obtain the first follicular map directly from the image processor.The map processor may be connected to the image processor via one ormore intermediate devices or channels and the map processor is arrangedto obtain the first follicular map from the image processor via the oneor more intermediate devices or channels. In an embodiment, the mapprocessor is connected to a storage unit, the image processor isconnected to the storage unit, the image processor is arranged to storethe first follicular map in the storage unit, and the map processor isarranged to obtain the first follicular map from the image processor byretrieving it from the storage unit. The retrieval from the storage unitmay occur substantially immediately after the first follicular map wasstored in the storage unit by the image processor. The retrieval fromthe storage unit may alternatively occur at a much later moment in timethan when the first follicular map was stored in the storage unit by theimage processor, to allow a later analysis of the first follicular map,for example, when a second follicular map has become available after aperiod of time, to allow to compare a change of the follicular map overtime to support the examination of symptoms of hair diseases.

The image processing algorithm performed on the first videodermoscopyimage IM1 to generate the first follicular map FM1 representing thefirst plurality of hair root positions in the first videodermoscopyimage IM1, may comprise any combination of suitable pattern recognitionalgorithms and qualification algorithms, such as binarization, adaptivethresholding, noise detection, blob detection, blob recombination, linetracking, hair crossing recombination, end detection, watersheddivision, and tip-follicle qualification.—The image processing algorithmmay be supplemented by a manual correction by operators, for, e.g.,removal of mistakes, addition of non-detected hair, removal of falselydetected hair, addition or removal of hair follicles. The spatialcoordinates of the hair follicles identified in the field of view of thefirst videodermoscopy image may be referred to as the first follicularmap FM1. The first follicular map FM1 thus represents the firstplurality of hair root positions in the first videodermoscopy image IM1.The first follicular map FM1 may be stored and/or presented as a list ofspatial coordinates, such as (x, y) coordinates in the firstvideodermoscopy image IM1, as a graphical representation, or in anyother suitable form. The first follicular map FM1 may, e.g., bepresented on screen together with the first videodermoscopy image, suchas side-by-side with the first videodermoscopy image or as an overlay onthe first videodermoscopy image.

FIG. 2 thus shows an embodiment of an analysis unit ANA′ for assessmentof hair condition, the analysis unit comprising an image processor IMParranged to at least perform an image processing algorithm on a firstvideodermoscopy image IM1 to obtain a first follicular map FM1representing a first plurality of hair root positions in the firstvideodermoscopy image IM1, and a map processor MPP arranged to analyseat least the first follicular map FM1 to determine an analysis resultANR1 suitable for assessment of hair condition.

FIG. 2 further that, in further embodiments, the analysis unit ANA′ maycomprise a map modification unit MOD. The image processor IMP isarranged to, as part of obtaining the first follicular map FM1,cooperate with the map modification unit MOD. The map modification unitMOD is arranged to present the first follicular map FM1 as obtained fromthe performing of the image processing algorithm on the firstvideodermoscopy image to a human assistant, and allow the humanassistant to review the first follicular map FM1 and to modify the firstfollicular map FM1 such as to, at least, add and/or remove one or morehair root positions from the first follicular map FM1. The firstfollicular map as reviewed and modified is thereafter used for analyzingat least the first follicular map to determine the analysis resultsuitable for assessment of hair condition. Using review by humanassistants may improve the quality of the follicular map significantly.In further embodiments, the map modification unit MOD is furtherarranged to present the first follicular map FM1 as obtained from theperforming of the image processing algorithm on the firstvideodermoscopy image IM1 to a plurality of human assistants, to alloweach of the human assistant to review the first follicular map and topropose to modify the first follicular map such as to, at least, addand/or remove one or more hair root positions from the first follicularmap. In these embodiments, the map modification unit MOD may be arrangedto compare the proposals from the plurality of human assistants forremoving one or more hair root positions from the first follicular mapFM1, and to decide from the comparison which hair root position of theproposed one or more hair root positions from the first follicular mapto delete. For example, the map modification unit MOD may be arranged touse a majority voting in deciding which of the proposed one or more hairroot positions is to be deleted. Using majority voting of a plurality ofreviews by human assistants may improve the quality of the follicularmap even further.

In the embodiments shown in FIG. 1 and FIG. 2, as well as in furtherembodiments, the map processor MPP may be arranged to, as part ofanalysing at least the first follicular map to determine the analysisresult, perform a statistical analysis of hair root distances betweenhair roots positions of the first plurality of hair root positions.

Herein, the map processor MPP may be arranged to, as part of performingthe statistical analysis of hair root distances between hair rootpositions, determine a hair root distance distribution, and determine atleast a first and a second relative contribution to the hair rootdistance distribution of at least a first and a second distributioncomponent function.

For example, the first and second relative contributions may be obtainedfrom, a two-component fit to the distribution, with the firstcontribution reflecting the dominant component for a specific hairdisorder and the second contribution reflecting the dominant componentfor healthy hair. Optionally more contributions may be used reflectingrespective dominant component for other specific hair disorders.

In an embodiment, the relative contribution of the first distributioncomponent function being an indication for a degree of a hair disorderof a first type. E.g., when the relative contribution is found to be ina first indicator range, such as larger than 35%, this may be anindication of androgenetic alopecia (AGA). An example is shown in FIG.3a and FIG. 3b . FIG. 3a shows the distribution of distances to allother hair follicles in the follicular map of a first, healthy, person.FIG. 3b shows the distribution of distances to all other hair folliclesin the follicular map of a second person who has AGA in an advancedstage. In each Figure, the resulting distribution, indicated as pointsP(r), is fitted in the low distance range (in this example, distancesr<600 μm) by a model consisting of a sum of two components: a firstcomponent labeled AGA that is a linear distribution, and a secondcomponent labeled non-AGA that is peaked at low values and has a varyingwidth. The first component represents a distribution that ischaracteristic for AGA. The second component represents a distributionthat is characteristic for healthy individuals. The relativecontribution of the first component provides a measure to assess AGAadvancement.

FIG. 4 shows an analysis unit ANA″ for assessment of hair conditionaccording to another embodiment. The analysis unit ANA″ comprises a mapprocessor MPP′. The map processor MPP′ is arranged to at least obtain afirst follicular map FM1 representing a first plurality of hair rootpositions in a first videodermoscopy image and a second follicular mapFM2 representing a second plurality of hair root positions in a secondvideodermoscopy image. The map processor MPP′ is further arranged toanalyse at least the first follicular map FM1 and the second follicularmap FM2 to determine an analysis result ANR2 suitable for assessment ofhair condition.

The map processor MPP′ may, similarly as described with respect to themap processors shown in FIG. 1 and FIG. 2, obtain the first and secondfollicular map FM1, FM2 from retrieving the maps from a storage,receiving them from a communication network, or receive them from theimage processor IMP′. For example, the image processor IMP′ may befurther arranged to perform an image processing algorithm on a secondvideodermoscopy image to generate the second follicular map representingthe second plurality of hair root positions in the secondvideodermoscopy image, and the map processor MPP′ may be arranged toobtain the second follicular map from the image processor.

Similar to analysis unit ANA′ shown in FIG. 2, the analysis unit ANA″may comprise a map modification unit MOD′. The image processor IMP isarranged to, as part of obtaining the first follicular map FM1 as wellas part of obtaining the second follicular map FM2, cooperate with themap modification unit MOD′. The map modification unit MOD′ is arrangedto present the first and second follicular maps FM1, FM2 as obtainedfrom the performing of the image processing algorithm on the first andsecond videodermoscopy image to a human assistant, and allow the humanassistant to review the first and second follicular map FM1, FM2 and tomodify the first and second follicular map FM1, FM2 such as to, atleast, add and/or remove one or more hair root positions from the firstand/or second follicular map FM1, FM2. The first and second follicularmap as reviewed and modified is thereafter used for analyzing at leastthe first and second follicular map to determine the analysis resultsuitable for assessment of hair condition.

In an embodiment, the map processor MPP′ is further arranged todetermine a common skin area from the first follicular map FM1 and thesecond follicular map FM2. This is illustrated in FIG. 5. FIG. 5schematically shows a first and second follicular map FM1, FM2 and thecommon skin area. The common skin area thus corresponds to a part OV1 ofthe first follicular map FM1 that corresponds to a part OV2 of thesecond follicular map FM2 which corresponds to the same skin area as thepart OV1 of the first follicular map FM1. These parts may further bereferred to as the common skin area OV1 of the first follicular map FM1and the common skin area OV2 of the second follicular map FM2. The mapprocessor MPP′ may be arranged to as part of determining the common skinarea from the first follicular map FM1 and the second follicular mapFM2, determine a transformation function TF12 which relates hair rootpositions in the first follicular map FM1 to hair root positions of thesame hair in the second follicular map FM2. The common skin area OV1 ofthe first follicular map FM1 may thus be related to the common skin areaOV2 of the second follicular map FM2 by transformation function TF12 asschematically illustrated in FIG. 5. When the first follicular map FM1relates to a first videodermoscopy image registered at a first moment intime, such as before a treatment, and the second follicular map FM2relates to a second videodermoscopy image registered at a second latermoment in time, such as after the treatment, analyzing differencesbetween the common skin area of the first follicular map FM1 and thecommon skin area of the second follicular map FM2 and/or analyzingdifferences between the common skin area of the first videodermoscopyimage IM1 and the common skin area of the second videodermoscopy imageIM2 may allow a largely improved precision compared to known techniques.Using the follicular maps to identify the common skin area, i.e.,corresponding skin areas in both follicular maps, largely improves theprecision of the analysis. Whereas prior art techniques relied stronglyon exactly the same positioning of the camera on the skin and the samefield of view, the use of the matching follicular maps makes theanalysis largely independent of size, shape and distortion of the areaused for the videodermoscopic analysis. The size, shape and distortionof the area of the skin registered on a videodermoscopy image may varysignificantly when two images are registered at different moments intime and/or different locations. For example, if the skin is stretchedor displaced by pressing the videodermoscopic lens, the actualmeasurement area may differ up to 30%, which results in an inaccurateanalysis with known techniques.

For example, identifying which of the hair root positions in the firstfollicular map FM1, and hence which hair in the first videodermoscopyimage IM1 corresponds to which of the hair root positions in the secondfollicular map FM2, and hence which hair in the second videodermoscopyimage IM2, allows an accurate determination of which hair has appearedand which hair has disappeared, based on tracking individual hair ratherthan mere statistics over the overlap area. E.g., instead of determiningthat the number of hair has increased from 100 to 105 for a specificsubject after a certain period of time, it may be determined that 5 hairwere lost and 10 came new. Such knowledge may be of relevance whenassessing certain kinds of hair disorder. For determination oftherapeutic effects of new substances in clinical trials, this techniqueand the corresponding precision improvement, may allow to reduce thenumber of test patient samples necessary to obtained conclusive result.

As shown in FIG. 4, the map processor MPP′ may a matching unit MAT. Thematching unit MAT may be arranged to at least relate hair root positionsin the second follicular map to hair root positions of the firstfollicular map in at least the common skin area to determine a pluralityof related hair root positions. Each related hair root position of ahair root in the second follicular map may thus be related to a hairroot position in the first follicular map of the same hair root. Thismay be performed as part of determining the common skin area, or afterthe common skin are has been determined. Hereby, the method determinesrelates hair root positions of the second plurality of hair rootpositions in the second videodermoscopy image to hair root positions ofthe first plurality of hair root positions in the first videodermoscopyimage in at least the common skin area to determine related hair rootpositions.

The map processor MPP′ may be arranged to, in determining the commonskin area from at least analyzing the first plurality of positions ofhair roots and the second plurality of positions of hair roots, findcorresponding positions of hair roots by minimizing their relativedistance in one or more iterations.

In embodiments, the matching unit MAP is arranged to, as part ofrelating hair root positions and/or while determining a common skin areafrom the first follicular map FM1 and the second follicular map FM2,initialize a transformation function TF12 and iteratively adapt thetransformation function TF12. The iterative adaption comprises:

-   -   applying the transformation function TF12 to the first plurality        of hair root positions of the first follicular map FM1 to obtain        a first plurality of transformed hair root positions,    -   relating the first plurality of transformed hair root positions        to the second plurality of hair root positions of the second        follicular map FM2,    -   determining relative distances between transformed hair root        positions of the first plurality of transformed hair root        positions and the related hair root positions of the second        plurality of hair root positions to obtain a correspondence        metric, and    -   adapting the transformation function TF12 to minimize the        correspondence metric.

In further embodiments, the matching unit MAP is arranged to, as part ofiteratively adapting the transformation function, further use at leastone parameter of hair associated with the transformed hair rootpositions and hair associated with the related hair root positions toobtain the correspondence metric, the at least one parameter comprisingat least one parameter from a group consisting of hair shaft diameter,hair length, hair growth, hair color.

In further embodiments, the matching unit MAP is arranged to, as part ofinitializing the transformation function TF, detect positions of a firstplurality of reference symbols REF1 on the skin in the firstvideodermoscopy image IM1, detect positions of a second plurality ofreference symbols REF2 on the skin in the second videodermoscopy imageIM2, initialize the transformation function TF12 to reflect atransformation from the positions of a first plurality of referencesymbols REF1 to the positions of a second plurality of reference symbolsREF2.

The first and second plurality of reference symbols REF1, REF2 may be aplurality of micro-tattoos on the skin, for example 2, 3, 4, 6, 9, 16 orany suitable number of micro-tattoos. The micro-tattoos may, as in knownmethods, be used to roughly position the videodermoscope at roughlycorresponding positions on the skin to register suitable videodermoscopyimages at subsequent moments in time.

The map processor MPP′ may be further arranged to at least analysedifferences between at least the common skin area OV1 in the firstfollicular map FM1 and the common skin area OV2 in the second follicularmap FM2 to determine the analysis result suitable for assessment of haircondition. The map processor MPP′ may thus analyze differences betweenhair root positions, number of hair roots and hair root density. Thefirst follicular map fm1 may, e.g., be associated with a firstvideodermoscopy image im1 registered before the start of a treatment,and the second follicular map FM2 may associated with a secondvideodermoscopy image IM2 registered after a certain duration of thetreatment. Analysing the differences may then give an analysis resultsuitable for supporting the examination of hair condition, in particularwhether symptoms have changed as a result of the treatment. The mapprocessor MPP′ may be arranged to, in determining the analysis result,identify an appearing of new hair roots in the common skin area in thesecond follicular map compared to the common skin area in the firstfollicular map. The map processor MPP′ may provide the appearing of newhair roots as an indication of new growth as part of the analysisresult. The map processor MPP′ may be arranged to, in determining theanalysis result, identify a disappearing of hair roots from the commonskin area in the second follicular map compared to the common skin areain the first follicular map. The map processor MPP′ may provide thedisappearing of hair roots as an indication of hair loss as part of theanalysis result. The map processor MPP′ may be arranged to, indetermining the analysis result, determine a difference in total numberof hair roots in the common skin area OV2 in the second follicular mapFM1 compared to the common skin area OV1 in the first follicular mapOV2. The map processor MPP′ may be arranged to, in determining theanalysis result, determine a difference in hair density in the commonskin area OV2 in the second follicular map FM2 compared to the commonskin area OV1 in the first follicular map FM1.

In further or alternative embodiments, the map processor MPP′ isarranged to at least analyse differences between at least the commonskin area in the first videodermoscopy image IM1 and the common skinarea in the second videodermoscopy image IM2 to determine the analysisresult suitable for assessment of hair condition. The map processor MPP′may thus analyze differences between hair in the common skin area of thefirst videodermoscopy image IM1 and hair in the common skin area in thesecond videodermoscopy image IM2. Individual hair may be compared as foreach hair in the first videodermoscopy image IM1, the related hair inthe second videodermoscopy image IM2 can be identified, e.g. by applyingthe transformation function TF12 to the hair root position from thefirst follicular map FM1 to find the related hair root position in thesecond follicular map FM2. The first videodermoscopy image IM1 may havebeen registered before the start of a treatment, and the secondvideodermoscopy IM2 image may have been registered after a certainduration of the treatment. Analysing the differences may then give ananalysis result suitable for supporting the examination of haircondition, in particular whether symptoms have changed as a result ofthe treatment. The map processor MPP′ may hereto be arranged to, inanalyse differences between at least the common skin area in the firstvideodermoscopy image and the common skin area in the secondvideodermoscopy image, determine differences between at least oneparameters of a group of parameters consisting of average hair diameter,hair diameter distribution, average hair length, hair lengthdistribution, hair colors, hair color distribution, and/or at least onehair density.

According to an exemplary embodiment, the first videodermoscopy imageIM1 was captured before shaving and the second videodermoscopy image IM2was captured after shaving, and the map processor MPP′ is arranged tocompare lengths of individual hairs between the common skin area in thefirst videodermoscopy image IM1 and lengths of the same individual hairsin the common skin area in the second videodermoscopy image IM2.Comparing the change in lengths may be performed by determining a lengthdecrease, such as to provide an indication of the hair length decreaseand thereby an indication of the shaving performance.

According to another exemplary embodiment, the first videodermoscopyimage IM1 was captured immediately or shortly after shaving and thesecond videodermoscopy image IM2 was captured significantly later aftershaving, such as after 3-5 days, and the map processor MPP′ is arrangedto compare lengths of individual hairs between common skin area in thefirst videodermoscopy image IM1 and lengths of the same individual hairsin the common skin area in the second videodermoscopy image IM2, todetermine changes of length—in particular length increases by hairgrowth—for the individual hairs, and to calculate estimates of thelengths of individual hairs immediately after shaving from the changesof lengths. Hereby, an indication of the quality of close shaving may beprovided. In case a razor blade arranged to pull hair out and cut thehair effectively below skin surface was used, the estimates may providenegative lengths of individual hair as a result of the shaving. Theanalysis result suitable for assessment of hair condition may thus be aset of negative lengths of individual hair, reflecting the haircondition after shaving, or one or more statistical parameters measuredon the set of negative lengths of individual hair reflecting statisticalperformance indicators of the hair condition after shaving.

The first videodermoscopy image IM1 may e.g. be captured a few minutes,a few hours, or 1 or 2 days after shaving. When capturing after 1 or 2days, the hair has generally grown enough for a reliable detection ofhair root positions. The second videodermoscopy image IM2 may e.g. becaptured 3-5 days after shaving, which give enough time between thecapturing of the images for the hair to grow such that a growth rate canbe estimated for a reliable and sufficiently accurate estimates of thelengths immediately after shaving. For example, the firstvideodermoscopy image IM1 may e.g. be captured 1 day after shaving andthe second videodermoscopy image IM2 may e.g. be captured 3 days aftershaving. As another example, the first videodermoscopy image IM1 maye.g. be captured 2 days after shaving and the second videodermoscopyimage IM2 may e.g. be captured 5 days after shaving.

According to another exemplary embodiment, the first videodermoscopyimage IM1 was captured before epilation and the second videodermoscopyimage IM2 was captured after epilation. The map processor MPP′ may bearranged to, e.g., compare presence and/or diameters and/or lengths ofindividual hair between the first videodermoscopy image captured from apart of a skin before epilation and presence and/or diameters and/orlengths of the same individual hair in a second videodermoscopy imagecaptured from the same part after epilation as part of an examination ofepilation performance on hair condition, in particular hair extraction,hair diameter and hair length. Hereby, an analysis result suitable forthe assessment of hair condition may be obtained which is indicative forthe epilation performance. This embodiment provides estimates of thepositions of individual hair follicles and the correspondence betweenhair follicle locations between the first and second follicular maps,which allows, e.g., to determine which hair was successfully extracted,to compare individual hair before and after epilation, to evaluate theremaining hair and, in particular when also incorporating regrowthparameters, to distinguish between empty and damaged hair follicles.

According to another exemplary embodiment, the first videodermoscopyimage IM1 was captured immediately or shortly after epilation and thesecond videodermoscopy image IM2 was captured significantly later afterepilation, such as after 3-5 days. The map processor MPP′ may bearranged to, e.g., analyze regrowth for diameter and length increase todetermine a degree of hair follicle damage as part of the analysisresult.

FIG. 6 shows an analysis unit ANA-VT according to another embodiment.The analysis unit ANA-VT comprises a map processor MPP-VT. The mapprocessor MPP-VT is arranged to at least obtain a first follicular mapFM1 representing a first plurality of hair root positions in a firstvideodermoscopy image and a sequence FM2-SEQ of second follicular mapsFM2-1, FM2-2, FM2-3, each representing a plurality of hair rootpositions in associated second videodermoscopy images IM2-1, IM2-2,IM2-3 of a sequence IM2-SEQ of different second videodermoscopy images.The second videodermoscopy images IM2-1, IM2-2, IM2-3 of the sequenceIM2-SEQ may correspond to videodermoscopy images acquired from differentlocations on the skin, for example as images from adjacent parts oroverlapping parts of the skin. The second videodermoscopy images IM2-1,IM2-2, IM2-3 of the sequence IM2-SEQ may correspond to videodermoscopyimages acquired from changing the position of the videodesmoscopebetween registering successive second videodermoscopy images, e.g.,while moving the videodesmocope along a part of a skin in a scanningdirection. The map processor MPP-VT is further arranged to analyse atleast the first follicular map FM1 and the sequence of second follicularmaps FM2-1, FM2-2, FM2-3 to determine an analysis result ANR2-VTsuitable for assessment of hair condition. The map processor MPP-VT mayalternatively or additionally be arranged to determine an analysisresult suitable for assessment of skin condition, such as detecting,measuring or monitoring skin color, skin color variation, presence andgrowth of birthmarks, naevus, scars, and their development over time.

The analysis unit ANA-VT shown in FIG. 6 comprises an image processorIMP-VT arranged to perform an image processing algorithm on each secondvideodermoscopy image of the sequence of second videodermoscopy imageIM2-1, IM2-2, IM2-3 to generate the sequence of second follicular mapsFM2-1, FM2-2, FM2-3, each second follicular map representing anassociated second plurality of hair root positions in the associatedsecond videodermoscopy image IM2-1, IM2-2, IM2-3. As illustrated in FIG.7, a videodermoscopy camera CAM or another suitable camera may be usedto obtain the sequence of second videodermoscopy image IM2-1, IM2-2,IM2-3 while moving the camera CAM along a part of a skin SKN in ascanning direction DIR. Moving the camera may be performed as acontinuous movement along the scanning direction and registering each ofthe of second videodermoscopy images of the sequence of secondvideodermoscopy images may be performed while the camera is moving.Moving the camera CAM may alternatively be performed in a step-wisemanner, where the moving comprises repositioning the camera betweensuccessive imaging locations of a sequence of different successiveimaging locations along the scanning direction for registering each ofthe second videodermoscopy images of the sequence of secondvideodermoscopy images at a respective one of the successive imaginglocations. The camera CAM may obtain the sequence of secondvideodermoscopy images such that successive second videodermoscopyimages of the sequence of second videodermoscopy images are partlyoverlapping. Hereby, the sequence of second videodermoscopy imageseffective registeres a large strip of the skin. The camera CAM mayobtain the sequence of second videodermoscopy images as a sequence ofstill images taken, for example, at a fixed or varying time interval ina range of 10 ms to 5 seconds, or at any other suitable time interval.The camera CAM may alternatively obtain the sequence of secondvideodermoscopy images as a video sequence having a frame rate in, forexample, a range of 10-100 Hz, e.g. at a frame rate of 16.7, 25, 50, 60or 100 Hz, or at any other suitable frame rate. The sequence may beprovided offline to the image processor IMP-VT. The sequence may beprovided real-time to the image processor IMP-VT, and the imageprocessor IMP-VT may be arranged to generate the sequence of secondfollicular maps FM2-1, FM2-2, FM2-3 real-time from the sequence ofsecond videodermoscopy images IM2-1, IM2-2, IM2-3.

The image processor IMP-VT may further be arranged to perform an imageprocessing algorithm on the first videodermoscopy IM1 to generate thefirst follicular maps FM1, but the first follicular maps FM1 may havebeen determined at an earlier moment in time and stored in a databaseVT-DB for retrieval when the analysis unit operates on a secondvideodermoscopy images of the same person for, e.g., obtaining ananalysis suitable for assessing a change in hair condition.

The map processor MPP-VT is further arranged to determine a common skinarea from the first follicular map FM1 and the sequence of secondfollicular maps FM2-1, FM2-3, FM2-3. Herein, the map processor MPP-VTmay be arranged to determine which second follicular map of the sequenceFM2-1, FM2-3, FM2-3 matches the first follicular map FM1 best, asillustrated in FIG. 8.

Hereto, the analysis unit ANA-VT may comprises a matching unit MAT-VT,similar to the embodiment described with reference to FIG. 4. Thematching unit MAT-VT may be arranged to at least relate hair rootpositions in each of the second follicular maps FM2-1, FM2-2, FM2-3 tohair root positions of the first follicular map FM1 in at least thecommon skin area to determine a plurality of related hair rootpositions. For each of the second follicular maps FM2-1, FM2-2, FM2-3,the matching unit MAT-VT aims to relate each related hair root positionof a hair root in respective the second follicular map to a hair rootposition in the first follicular map FM1 of the same hair root. This maybe performed as part of determining the common skin area, or after thecommon skin are has been determined. Hereby, the method relates, foreach of the second follicular maps FM2-1, FM2-2, FM2-3, hair rootpositions of the respective second plurality of hair root positions inthe respective second videodermoscopy image to hair root positions ofthe first plurality of hair root positions in the first videodermoscopyimage in at least the common skin area to determine related hair rootpositions. The map processor MPP-VT is arranged to, in determining thecommon skin area from at least analyzing the first plurality ofpositions of hair roots in the first follicular map FM1 and the secondplurality of positions of hair roots in each of the second follicularmaps FM2-1, FM2-2, FM2-3, find corresponding positions of hair roots byminimizing their relative distance in one or more iterations. Referenceis further made to the description of the matching unit MAT of FIG. 4.

FIG. 8 schematically shows, on the left, a first videodermoscopy imageIM1 and its first follicular map FM1. The right column shows a sequenceof second videodermoscopy images IM2-1, IM2-2, IM2-3 and the associatedsequence of second follicular maps FM2-1, FM2-2, FM2-3. The cameraposition was moved by half of the image height between IM2-1 and IM2-2,and again between IM2-2 and IM2-3, thereby generating overlappingimages. However, the images may also be adjacent or have a gap inbetween, as long as the size of the overlapping area between the firstfollicular map FM1 and best matching second follicular map of thesequence is adequate for determining an analysis result. It may be seenfrom the Figure that the second follicular map FM2-2 of the sequencematches the first follicular map FM1 best. Thus, the location of thesecond follicular map FM2-2 of the sequence matches that of the firstfollicular map FM1 best, and a reliable analysis result may bedetermined from the second follicular map FM2-2 of the sequence ofsecond follicular map, the first follicular map FM1, and, inembodiments, the second videodermoscopy image IM2-2 of the sequence ofsecond videodermoscopy images and the first videodermoscopy image IM1.

The use of a sequence of second videodermoscopy images IM2-1, IM2-2,IM2-3 and matching a prior first follicular map FM1 with the secondfollicular maps FM2-1, FM2-2, FM2-3 allows to refrain from micro-tattoosas reference symbols applied to the skin to allow imaging roughly thesame skin area at different moments in time. This may give some cosmeticand physical relief to persons subject to a hair condition or skincondition monitoring or treatment. Further, some countries do not allowmicro-tattoos, e.g. because they are considered to violate a person'sphysical integrity; some countries do not allow them at all, and othercountries not for cosmetic purposes. The system presented here maytherefore provide a virtual tattoo, where the first follicular map FM1acts as a robust reference for identifying a position on a person'sskin, and, optionally, also as an identification of the person. Hereby,a high-quality analysis result can be obtained.

In an embodiment, the analysis unit is arranged to provide a feedbacksignal indicative of the quality of the match between the firstfollicular map FM1 and the sequence of the second follicular maps,thereby allowing a person or another system to react on the signal. In afurther embodiment, the virtual tattoo is used real-time and theanalysis unit provides a feedback signal to a person operating thecamera once the analysis unit detects that there is a match between thefirst follicular map FM1 and one of the second follicular maps of thesequence FM2-SEQ. This allows the person to more precisely position thecamera under guidance of the analysis unit's feedback signal to find anoptimally matching area. The virtual tattoo may thus provide a positionon a person's skin.

FIG. 9 shows another analysis unit ANA′″ for assessment of haircondition according to another embodiment. The analysis unit ANA′″ shownin FIG. 6 differs from the analysis unit ANA″ shown in FIG. 4 in thatthe analysis unit ANA′″ further comprises a storage interface unit SIFarranged to cooperate with a storage unit STOR. Storage unit STOR isshown to be external to the analysis unit ANA′″, but may in alternativeembodiments ne an integral part of analysis unit ANA′″. Storage unitSTOR may be a cloud device, and may as such be connected to the analysisunit ANA′″ permanently or only when the analysis unit ANA′″ connects tothe storage unit STOR. The storage interface unit SIF is arranged tostore the follicular maps FM1, FM2, and optionally the videodermoscopyimages IM1, IM2, in the storage unit STOR after the follicular maps FM1,FM2 have been obtained from the image processor IMP′ or the mapmodification unit MOD. The storage interface unit SIF is furtherarranged to retrieve the follicular maps FM1, FM2, and optionally thevideodermoscopy images IM1, IM2, from the storage unit STOR foranalysis.

FIG. 10 shows another analysis unit ANA″″ for assessment of haircondition according to another embodiment. The analysis unit ANA′″ shownin FIG. 10 differs from the analysis unit ANA′″ shown in FIG. 9 in thatthe analysis unit ANA″″ does not comprise the image processor IMP′ andthe map modification unit MOD. The image processor IMP′ and the mapmodification unit MOD′ are instead provided as part of a separate unitshown as image provided IMPRO. The image provider IMPRO furthercomprises a first storage interface unit SIF1 arranged to cooperate witha storage unit STOR. Storage unit STOR may be a cloud device, and may assuch be connected to the image provider IMPRO and the analysis unitANA′″ permanently or only when image provider IMPRO or the analysis unitANA′″ connects to the storage unit STOR. The storage interface unit SIFis arranged to store the follicular maps FM1,

FM2, and optionally the videodermoscopy images IM1, IM2, in the storageunit STOR after the follicular maps FM1, FM2 have been obtained from theimage processor IMP′. The analysis unit ANA″″ comprises a second storageinterface unit SIF2 arranged to cooperate with the storage unit STOR.The second storage interface unit SIF2 is arranged to retrieve thefollicular maps FM1, FM2, and optionally the videodermoscopy images IM1,IM2, from the storage unit STOR for analysis.

FIG. 11 shows a zero-loss processor ZERLPROC according to an embodiment.The zero-loss processor ZERLPROC is arranged to receive a plurality offirst videodermoscopy input images IM1A, IM1B. The plurality of firstvideodermoscopy input images IM1A, IM1B is obtained from taking asequence of videodermoscopy images at short time intervals, e.g. secondsor minutes apart while rearranging the camera or the hair in betweensuccessive images. The hair may e.g. be non-combed and combed, combed indifferent directions—one may observe differences in hair directionbetween figure IM1A and IM1B-, parted or otherwise rearranged in asuitable manner. The camera may e.g. be shifted a small distance, e.g.,1-10 mm, between successive images. The camera may be a digital stillcamera. The camera may alternatively be a video camera arranged toprovide a sequence of video images, a successive sequence of videoimages or a sub-set of successive video images providing the pluralityof first videodermoscopy input images.

The zero-loss processor ZERLPROC comprises an input image processorIM2FM arranged to perform an image processing algorithm on each of thefirst videodermoscopy input images IMA1, IMA2 of the plurality of firstvideodermoscopy input images IM1A, IM1B to generate a plurality of firstfollicular maps FM1A, FM1B, each first follicular map representing afirst plurality of hair root positions in the corresponding firstvideodermoscopy input image.

The zero-loss processor ZERLPROC comprises a combiner COMB. The combinerCOMB comprises a matching unit MAT, a follicular map combiner COMBFM. Infurther embodiments, the combiner COMB may further comprise an inputimage combiner COMBIM.

The matching unit MAT in the embodiment shown in FIG. 11 may correspondto the matching unit MAT described with reference to FIG. 4. Thematching unit MAT in the embodiment shown in FIG. 11 may be arranged toat least relate hair root positions in a second map FM1B of theplurality of first follicular maps to hair root positions of the firstmap FM1A in at least a common skin area to determine a plurality ofrelated hair root positions. Each related hair root position of a hairroot in the second map FM1B may thus be related to a hair root positionin the first map FM1A of the same hair root. This may be performed aspart of determining the common skin area, or after the common skin arehas been determined. Reference is further made to the description of thematching unit MAT with reference to FIG. 4. As shown, the matching unitmay determine a transformation function TF12 which relates hair rootpositions in the first map FM1A of the plurality of first follicularmaps FM1A, FM1B to hair root positions of the same hair in the secondmap FM1B. Just for illustration and in order to not obscure the Figure,the size, shape and position of the input images are drawn to reflectthe same complete common skin area in FIG. 12.

The combiner COMB shown in FIG. 11 is arranged to obtain the pluralityof first follicular maps FM1A, FM1A from the input image processorIM2FM. The combiner COMB may further be arranged to obtain the pluralityof first videodermoscopy input images IM1A, IM1B from the input imageprocessor. The follicular map combiner COMBFM is arranged to determine acombined first follicular map FM1 from the plurality of first follicularmaps FM1A, FM1A. The input image combiner COMBIM is, in furtherembodiments, arranged to determine a combined input image IM1 fromplurality of first videodermoscopy input images IM1A, IM1B using theplurality of first follicular maps FM1A, FM1A.

The zero-loss processor ZERLPROC may be arranged to output the combinedfirst follicular map FM1, which may be used as the first or secondfollicular map in the embodiments described above with reference to FIG.1-FIG. 10. In further embodiments, the zero-loss processor ZERLPROC maybe arranged to output the combined input image IM1, which may be used asthe first or second videodermoscopy image in the embodiments describedabove with reference to FIG. 1-FIG. 10.

Similar to analysis unit ANA′ shown in FIG. 2, the zero-loss processorZELFPROC may comprise a map modification unit MOD′, similar to the onedescribed with reference to FIG. 4. In such embodiment, the input imageprocessor IM2FM is arranged to, as part of obtaining the plurality offirst follicular maps FM1A, FM1B, cooperate with the map modificationunit MOD′. The map modification unit MOD′ is arranged to present theplurality of first follicular maps FM1A, FM1B as obtained from theperforming of the image processing algorithm on the plurality of firstvideodermoscopy input images to a human assistant, and to allow thehuman assistant to review the plurality of first follicular maps FM1A,FM1B and to modify the first follicular maps FM1A, FM1B such as to, atleast, add and/or remove one or more hair root positions from the firstfollicular maps FM1A, FM1B. The plurality of first follicular maps asreviewed and modified is thereafter used for combining the plurality offirst follicular maps FM1A, FM1B and, in embodiments, the plurality offirst videodermoscopy input images IM1A, IM1B. The quality of theplurality of first videodermoscopy input images may hereby be improved,as human assistants may be able to identify false positive and or falsenegatives and may be able to correct errors made by the hardware of thesystem.

The zero-loss processor ZERLPROC may be used as an alternative to imageprocessor IMP. The zero-loss processor ZERLPROC may be used in analternative embodiment of image processor IMP′.

FIG. 12 schematically shows examples of videodermoscopic images andfollicular maps to illustrate the operation of a zero-loss processor ofFIG. 11, in particular of the operation of the combiner COMB. FIG. 12schematically shows two input images IM1A, IM1B of a plurality of firstvideodermoscopy input images IM1A,

IM1B. The two input images schematically represent two images ofsubstantially the same skin part taken a few seconds—e.g., 5seconds—apart with the hair having been combined in the meantime. FIG.12 also schematically shows two maps FM1A, FM2A of a plurality of firstfollicular maps FM1A, FM1A, each reflecting the plurality of hair rootpositions in the corresponding first videodermoscopy input images IM1A,IM1B.

It may be observed in FIG. 12 that the first input image IM1A and thesecond input IM1B of substantially the same skin part show—apart fromdifferences in direction of some of the hairs—three differences,indicated by double arrows: the first input image IM1A shows a hair inthe bottom left quadrant that is not visible in the second input imageIM1B, and the associated hair root position is also present in first mapFM1A but absent in second map M1B. Similarly, another two hairs arevisible in the second input image IM1B that are not visible in firstinput image 1A, and similarly for the two associated hair root positionsthat are in second map FM1B but not in first map FM1A.

As the two maps FM1A and FM1B are matched by the matching unit MAT suchthat the positions of individual hair appearing in both maps are known,the combiner COMB is arranged to identify which hair root positions infirst map FM1A do not appear in second map FM1B and vice versa. Addingthe hair root positions that do not appear in first map FM1A but that doappear in second map FM1B to the hair root positions in first map FM1Amay thus provide a combined first follicular map FM1. The follicular mapcombiner COMBFM may thus be arranged to determine a combined firstfollicular map FM1 from the plurality of first follicular maps FM1A,FM1A. Likewise, adding from the second input image IM1B the hair thatrelates to hair root positions that do not appear in first map FM1A butthat do appear in second map FM1B to the first input image IM1A may thusprovide a combined input image IM1. The input image combiner COMBIM maythus be arranged to determine a combined input image IM1 from pluralityof first videodermoscopy input images IM1A, IM1B using the plurality offirst follicular maps FM1A, FM1A.

Creating a combined first follicular map FM1 from a plurality of firstvideodermoscopy input images and/or creating a combined input image IM1from plurality of first videodermoscopy input images results in,respectively, a follicular map and/or a videodermoscopy image with anincreased detection efficiency of hair root positions and/or hair. Whencombined with any of the other embodiments described, this may result ina more precise and/or more reliable and/or more consistent analysisresult.

FIG. 13 schematically shows a system SYS for assessment of haircondition. The system SYS comprises an upload unit UPL, an analysis unitANU, and a presentation unit PRES. The upload unit UPL is arranged toreceive one or more videodermoscopy images, e.g. from a dermatologist oran assistant thereof that registered the videodermoscopy images on ascalp from a patient, e.g. by feeding into a scanner, by retrieving froma storage for example at the dematologists'clinic, or by retrieving froma communication network. The one or more videodermoscopy images compriseat least the first videodermoscopy image. The upload unit UPL is furtherarranged to upload the one or more videodermoscopy images to theanalysis unit, for example via a communication network, or via e-mail,or as a hardcopy via surface mail or a delivery service. The analysisunit ANU is arranged to receive the one or more videodermoscopy imagesfrom the upload unit UPL. The analysis unit ANU is arranged to obtain avideodermoscopic analysis result from the one or more videodermoscopyimages. The videodermoscopic analysis result comprises at least one ofthe analysis result suitable for assessment of hair condition asobtained by one of the analysis units described with reference to FIG.1-FIG. 10, and an examination result derived from the analysis resultresult. The presentation unit PRES is arranged to receive thevideodermoscopic analysis result from the analysis unit ANU and topresent at least part of the analysis result to a user. The presentationunit PRES may be arranged to present at least part of the analysisresult to a user on, for example, a display, on paper, in acomputer-readable data format, in a human-readable form or on a datastorage medium, in a qualitative or quantitative manner, as a graphicalor textual, such as table or phrases, representation. The user may,e.g., be a patient, a general practitioner, a dermatology nurse, adermatologist, or a scientist.

FIG. 13 shows that the system SYS may further comprise a result checkunit RCHK. The result check unit RCHK is arranged to receive thevideodermoscopic analysis result from the analysis unit ANU. The resultcheck unit RCHK is arranged to review the videodermoscopic analysisresult and to modify the videodermoscopic analysis result. For example,the videodermoscopic analysis result may be changed, supplemented,summarized or reformatted. The videodermoscopic analysis result may e.g.be supplemented with a diagnosis of a hair disorder, a treatmentproposal or a treatment change. E.g., an expert system or a human expertdermatologist may draw a diagnosis as the presence, or lack of presence,of AGA. The result check unit RCHK is arranged to provide thevideodermoscopic analysis result as modified to the presentation unit toallow the presentation unit to present at least part of thevideodermoscopic analysis result as modified to the user. The resultcheck unit RCHK may be connected to the analysis unit ANU via acommunication network such as the internet, whereby the result check andthe image processing may take place at different geographical locations.The result check unit RCHK may alternatively be directly connected tothe analysis unit ANU and part of a single unit, e.g., the analysis unitANU and the result check unit RCHK may be implemented in a personalcomputer of a dermatologist.

As shown in FIG. 13, the upload unit UPL may be connected to theanalysis unit ANU via a communication network COMM. The communicationnetwork COMM may be a virtual private network. The communication networkCOMM may be the Internet. Hereby, videodermoscopic images registered atvarious places, e.g. at various dermatologic clinics, may be sent viathe internet to the analysis unit ANU at a centralized location, atwhich centralized location a consistent and quality-controlledprocessing may be performed to obtain the follicular maps and theanalysis results. The processing at the centralized location simplifiesthe use of a pool of well-trained staff to do the review andmodification of the follicular maps described above with reference tothe map modification unit MOD.

As shown in FIG. 13, the presentation unit PRES may be connected to theanalysis unit ANU via a communication network. The communication networkmay be the same virtual private network, another virtual privatenetwork, or, for example, the Internet. The analysis unit ANU may thusbe at a central location, and the presentation unit PRES may be at ageneral practitioner, a nurse, a patient, or elsewhere.

In embodiments, the system SYS comprises a user terminal TERM. The userterminal TERM comprises the upload unit UPL and the presentation unitPRES. The user terminal TERM is connected to the analysis unit ANU via acommunication network COMM. The user terminal TERM may, e.g., be acomputer at a dermatologist's clinic that can connect via the internet,e.g. using a virtual private network, to the analysing unit ANU at acentralized location.

FIG. 14 schematically shows a method M_ANA for assessment of haircondition according to an embodiment. The method M_ANA comprisesobtaining OBT a first follicular map FM1 representing a first pluralityof hair root positions in a first videodermoscopy image. The methodM_ANA comprises analysing M_MPP at least the first follicular map todetermine an analysis result ANR1 suitable for assessment of haircondition. Reference is further made to FIG. 1.

FIG. 15 schematically shows a method M_ANA′ for assessment of haircondition according to a further embodiment. The method M_ANA′ comprisesperforming M_IMP an image processing algorithm on a firstvideodermoscopy image IM1 to obtain a first follicular map FM1representing a first plurality of hair root positions in the firstvideodermoscopy image. The method M_ANA′ further comprises analysing

M_MPP at least the first follicular map to determine an analysis resultANR1 suitable for assessment of hair condition. The method M_ANA′ mayfurther comprise a present-and-modify option M_MOD comprising presentingthe first follicular map as obtained from the performing of the imageprocessing algorithm on the first videodermoscopy image to a humanassistant, and allow the human assistant to review the first follicularmap and to modify the first follicular map such as to, at least, addand/or remove one or more hair root positions from the first follicularmap.

FIG. 16 schematically shows a method M_ANA″ for assessment of haircondition according to again a further embodiment. The method M_ANA′″comprises performing M_IMP′ an image processing algorithm on a firstvideodermoscopy image IM1 to obtain a first follicular map FM1representing a first plurality of hair root positions in the firstvideodermoscopy image and performing M_IMP′ an image processingalgorithm on a second videodermoscopy image to obtain the secondfollicular map representing the second plurality of hair root positionsin the first videodermoscopy image to obtain FM2 a second follicular maprepresenting a second plurality of hair root positions in a secondvideodermoscopy image. The method M_ANA′″ may further comprise apresent-and-modify option M_MOD′ comprising presenting the firstfollicular map as obtained from the performing of the image processingalgorithm on the first videodermoscopy image to a human assistant, andallow the human assistant to review the first follicular map and tomodify the first follicular map such as to, at least, add and/or removeone or more hair root positions from the first follicular map, andpresenting the second follicular map as obtained from the performing ofthe image processing algorithm on the second videodermoscopy image to ahuman assistant, and allow the human assistant to review the secondfollicular map and to modify the second follicular map such as to, atleast, add and/or remove one or more hair root positions from secondfirst follicular map. The method M_ANA′″ may comprises determining acommon skin area from the first follicular map FM1 and the secondfollicular map FM2.

The method may comprise uploading one or more videodermoscopy images toan analysis unit via a communication network, for letting the analysisunit perform the method according to any one of the embodiments above,and receiving the videodermoscopic analysis result from the analysis viathe communication network.

In a further embodiment, the method comprises obtaining a sequence ofsecond follicular maps, each second follicular map representing a secondplurality of hair root positions in an associated second videodermoscopyimage of a corresponding sequence of different second videodermoscopyimages, and determining a common skin area from the first follicular mapand at least one of the second follicular maps of the sequence of secondfollicular maps. The first follicular map may thus effectively act as alocation reference, and could be considered to function as a virtualtattoo. With this embodiment, the method may not just be arranged fordetermining an analysis result suitable for assessment of haircondition, but the method may additionally or alternatively be arrangedfor determining an analysis result suitable for assessment of skincondition.

The method may further comprise receiving one or more videodermoscopyimages by an upload unit, uploading the one or more videodermoscopyimages from the upload unit to an analysis unit via a communicationnetwork, for letting the analysis unit perform the method, andpresenting at least part of the videodermoscopic analysis result to auser.

FIG. 17 schematically shows a method of zero-loss videodermoscopic imageprocessing M-ZERL according to an embodiment. The method may further bereferred to as zero-loss method M_ZERL.

The zero-loss method M_ZERL comprises receiving a plurality of firstvideodermoscopy input images IM1A, IM1B. The plurality of firstvideodermoscopy input images IM1A, IM1B is obtained from taking asequence of videodermoscopy images at short time intervals, e.g. secondsor minutes apart while rearranging the camera or the hair in betweensuccessive images. The hair may e.g. be non-combed and combed, combed indifferent directions, parted or otherwise rearranged in a suitablemanner. The camera may e.g. be shifted a small distance, e.g., 1-10 mm,between successive images. The camera may be a digital still camera. Thecamera may alternatively be a video camera arranged to provide asequence of video images, a successive sequence of video images or asub-set of successive video images providing the plurality of firstvideodermoscopy input images.

The zero-loss method M_ZERL comprises performing an image processingalgorithm on each of the first videodermoscopy input images IMA1, IMA2of the plurality of first videodermoscopy input images IM1A, IM1B togenerate a plurality of first follicular maps FM1A, FM1 B, each firstfollicular map representing a first plurality of hair root positions inthe corresponding first videodermoscopy input image.

The zero-loss method M_ZERL comprises relating M_MAT hair root positionsin a second map FM1 B of the plurality of first follicular maps to hairroot positions of the first map FM1A in at least a common skin area todetermine a plurality of related hair root positions. Each related hairroot position of a hair root in the second map FM1 B may thus be relatedto a hair root position in the first map FM1A of the same hair root.This may be performed as part of determining the common skin area, orafter the common skin area has been determined. Reference is furthermade to the description of the matching unit MAT with reference to FIG.4.

The zero-loss method M_ZERL comprises determining M_COMBFM a combinedfirst follicular map FM1 from the plurality of first follicular mapsFM1A, FM1A.

The zero-loss method M_ZERL may further comprise determining M_COMBIM acombined input image IM1 from the plurality of first videodermoscopyinput images IM1A, IM1B using the plurality of first follicular mapsFM1A, FM1A.

The zero-loss method M_ZERL may further comprise outputting the combinedfirst follicular map FM1. The zero-loss method M_ZERL may compriseoutputting the combined first follicular map FM1 for use as the first orsecond follicular map in any one of the embodiments described above withreference to FIG. 1-FIG. 16.

The zero-loss method M_ZERL may further comprise outputting the combinedinput image IM1. The zero-loss method M_ZERL may further compriseoutputting the combined input image IM1 for use as the first or secondvideodermoscopy image in any one of the embodiments described above withreference to FIG. 1-FIG. 16.

The zero-loss method M_ZERL may further comprise a present-and-modifyoption M_MOD′ comprising presenting the plurality of first follicularmaps FM1A, FM1 B as obtained from the performing of the image processingalgorithm on the plurality of first videodermoscopy input images IM1A,IM1 B to a human assistant, and allow the human assistant to review theplurality of first follicular maps FM1A, FM1 B and to modify the firstfollicular maps FM1A, FM1 B such as to, at least, add and/or remove oneor more hair root positions from the first follicular maps FM1A, FM1 B.The plurality of first second follicular maps as reviewed and modifiedis thereafter used for combining the plurality of first follicular mapsFM1A, FM1 B and, in embodiments, the plurality of first videodermoscopyinput images IM1A, IM1 B.

FIG. 18 shows a computer readable medium CRMED comprising a computerprogram product CPP, the computer program product CPP comprisinginstructions for causing a processor apparatus to perform a methodaccording to any one embodiment or a part of thereof. The computerprogram product CPP may be embodied on the computer readable mediumCRMED as physical marks or by means of magnetization of the computerreadable medium CPP. However, any other suitable embodiment isconceivable as well. Furthermore, it will be appreciated that, althoughthe computer readable medium CRMED is shown in FIG. 18 as an opticaldisc, the computer readable medium CRMED may be any suitable computerreadable medium, such as a hard disk, solid state memory, flash memory,etc., and may be non-recordable or recordable. The computer programproduct CPP may thus comprise a computer program comprising instructionsarranged to, when executed by a computer, execute at least part of themethod of any one of the embodiments described above.

It should be noted that the above-mentioned embodiments illustraterather than limit the invention, and that those skilled in the art willbe able to design many alternative embodiments.

The invention may also be implemented in a computer program for runningon a computer system, at least including code portions for performingsteps of a method according to the invention when run on a programmableapparatus, such as a computer system or enabling a programmableapparatus to perform functions of a device or system according to theinvention. The computer program may for instance include one or more of:a subroutine, a function, a procedure, an object method, an objectimplementation, an executable application, an applet, a servlet, asource code, an object code, a shared library/dynamic load libraryand/or other sequence of instructions designed for execution on acomputer system. The computer program may be provided on a data carrier,such as a CD-type optical disc, a DVD-type optical disc, a hard disk, ordiskette, stored with data loadable in a memory of a computer system,the data representing the computer program. The data carrier may thus bea tangible data carrier. The data carrier may be a data connection, suchas a telephone cable or a network cable. The data carrier may further bea non-tangible data carrier such as a wireless connection.

In the claims, any reference signs placed between parentheses shall notbe construed as limiting the claim. Use of the verb “comprise” and itsconjugations does not exclude the presence of elements or steps otherthan those stated in a claim. The article “a” or “an” preceding anelement does not exclude the presence of a plurality of such elements.The invention may be implemented by means of hardware comprising severaldistinct elements, and by means of a suitably programmed computer. Inthe device claim enumerating several means, several of these means maybe embodied by one and the same item of hardware. The mere fact thatcertain measures are recited in mutually different dependent claims doesnot indicate that a combination of these measures cannot be used toadvantage.

1. An analysis unit for assessment of hair condition, the analysis unitcomprising a map processor, the map processor being configured to:obtain a first follicular map representing a first plurality of hairroot positions in a first videodermoscopy image, obtain a secondfollicular map representing a second plurality of hair root positions ina second videodermoscopy image, determine a common skin area from thefirst follicular map and the second follicular map, relate hair rootpositions in the second follicular map to hair root positions of thefirst follicular map in the common skin area to determine a plurality ofrelated hair root positions, each related hair root position of a hairroot in the second follicular map being related to a hair root positionin the first follicular map of the same hair root, and compare a changein condition of individual hair between the first and secondvideodermoscopy image to determine the analysis result suitable forassessment of hair condition.
 2. The analysis unit according to claim 1,the analysis unit further comprising an image processor, wherein: theimage processor being configured to perform an image processingalgorithm on a first videodermoscopy image to generate the firstfollicular map representing the first plurality of hair root positionsin the first videodermoscopy image, and the map processor beingconfigured to obtain the first follicular map from the image processor.3. The analysis unit according to claim 2, the image processor furtherbeing configured to perform the image processing algorithm on a secondvideodermoscopy image to generate the second follicular map representingthe second plurality of hair root positions in the secondvideodermoscopy image, and the map processor being configured to obtainthe second follicular map from the image processor.
 4. The analysis unitaccording to claim 2, the image processor being configured to, as partof obtaining the first follicular map, cooperate with a map modificationunit, the map modification unit being configured to: present the firstfollicular map as obtained from the performing of the image processingalgorithm on the first videodermoscopy image to a human assistant, andallow the human assistant to review the first follicular map and tomodify the first follicular map such as to, at least, add and/or removeone or more hair root positions from the first follicular map.
 5. Theanalysis unit according to claim 1, the map processor being furtherconfigured to: obtain a sequence of second follicular maps, each secondfollicular map representing a second plurality of hair root positions inan associated second videodermoscopy image of a corresponding sequenceof different second videodermoscopy images, and determine the commonskin area from the first follicular map and at least one of the secondfollicular maps of the sequence of second follicular maps.
 6. Theanalysis unit according to claim 5, the map processor being furtherconfigured to: analyze differences between the common skin area in thefirst follicular map and the common skin area in the second follicularmap to determine an analysis result suitable for assessment of skincondition.
 7. The analysis unit according to claim 1, the map processorbeing further configured to, in determining the analysis result:identify an appearing of new hair roots in the common skin area in thesecond follicular map compared to the common skin area in the firstfollicular map, and/or identify a disappearing of hair roots from thecommon skin area in the second follicular map compared to the commonskin area in the first follicular map.
 8. The analysis unit according toclaim 1, the map processor being further configured to analyzedifferences between at least the common skin area in the firstvideodermoscopy image and the common skin area in the secondvideodermoscopy image to determine the analysis result suitable forassessment of hair condition.
 9. The analysis unit according to claim 8,the map processor being further configured to, in analyzing differencesbetween at least the common skin area in the first videodermoscopy imageand the common skin area in the second videodermoscopy image, comparelengths of individual hair between the first videodermoscopy imagecaptured from a part of a skin, such as part of a human scalp, beforeshaving and lengths of the same individual hair in a secondvideodermoscopy image captured from the same part after shaving as partof an examination of shaving performance on hair condition, inparticular hair length.
 10. The analysis unit according to claim 8, themap processor being further configured to, in analyzing differencesbetween at least the common skin area in the first videodermoscopy imageand the common skin area in the second videodermoscopy image, comparelengths of individual hairs between a first videodermoscopy imagecaptured from a part of a skin, such as part of a human scalp,immediately after shaving and a second videodermoscopy image capturedfrom the same part one or more days after shaving, and to calculateestimates of the lengths of individual hairs immediately after shavingfrom the change of lengths.
 11. The analysis unit according to claim 8,the map processor being further configured to, in analyzing differencesbetween at least the common skin area in the first videodermoscopy imageand the common skin area in the second videodermoscopy image, comparepresence and/or diameters and/or lengths of individual hair between thefirst videodermoscopy image captured from a part of a skin beforeepilation and presence and/or diameters and/or lengths of the sameindividual hair in a second videodermoscopy image captured from the samepart after epilation as part of an examination of epilation performanceon hair condition, in particular hair extraction, hair diameter and hairlength.
 12. The analysis unit according to claim 8, the map processorbeing further configured to, in analyzing differences between at leastthe common skin area in the first videodermoscopy image and the commonskin area in the second videodermoscopy image, compare presence and/ordiameters and/or lengths of individual hair between a firstvideodermoscopy image captured from a part of a skin immediately orshortly after epilation and a second videodermoscopy image captured fromthe same part one or more days after epilation, and to calculateestimates of the quality of epilation such as percentage of successfulepilation and/or diameter and/or lengths of individual hair immediatelyafter epilation from the change of diameters and/or lengths.
 13. Theanalysis unit according to claim 1, the analysis unit further comprisinga zero-loss processor, the zero-loss processor being configured to:receive a plurality of first videodermoscopy input images captured as asequence of videodermoscopy images, perform an image processingalgorithm on each of the first videodermoscopy input images of theplurality of first videodermoscopy input images to generate a pluralityof first follicular maps, each first follicular map representing a firstplurality of hair root positions in the corresponding firstvideodermoscopy input image, relate hair root positions in a second mapof the plurality of first follicular maps to hair root positions of afirst map in at least a common skin area of the first map and the secondmap to determine a plurality of related hair root positions, anddetermine a combined first follicular map from the plurality of firstfollicular maps.
 14. The analysis unit according to claim 13, thezero-loss processor being configured to output the combined firstfollicular map to the image processor for use as the first or secondfollicular map.
 15. The analysis unit according to claim 13, thezero-loss processor being configured to output the combined input imageto the image processor for use as the first or second videodermoscopyimage.
 16. A system for assessment of hair condition, the systemcomprising: an upload unit, an analysis unit according for assessment ofhair condition, the analysis unit comprising a map processor, the mapprocessor being configured to: obtain a first follicular maprepresenting a first plurality of hair root positions in a firstvideodermoscopy image, obtain a second follicular map representing asecond plurality of hair root positions in a second videodermoscopyimage, determine a common skin area from the first follicular map andthe second follicular map, relate hair root positions in the secondfollicular map to hair root positions of the first follicular map in thecommon skin area to determine a plurality of related hair rootpositions, each related hair root position of a hair root in the secondfollicular map being related to a hair root position in the firstfollicular map of the same hair root, and compare a change in conditionof individual hair between the first and second videodermoscopy image todetermine the analysis result suitable for assessment of hair condition,and a presentation unit, wherein the upload unit is configured toreceive one or more videodermoscopy images, the one or morevideodermoscopy images including at least the first videodermoscopyimage and to upload the one or more videodermoscopy images to theanalysis unit, wherein the analysis unit is configured to receive theone or more videodermoscopy images from the upload unit and to obtain avideodermoscopic analysis result from the one or more videodermoscopyimages, the videodermoscopic analysis result including at least one of:the analysis result suitable for assessment of hair condition, and anexamination result derived from at least one of the analysis resultsuitable for assessment of hair condition, and wherein the presentationunit is configured to receive the videodermoscopic analysis result fromthe analysis unit and to present at least part of the analysis result toa user.
 17. The system according to claim 16, the system furthercomprising a result check unit, the result check unit being configuredto: receive the videodermoscopic analysis result from the analysis unit,review the videodermoscopic analysis result and to modify thevideodermoscopic analysis result, and provide the videodermoscopicanalysis result as modified to the presentation unit to allow thepresentation unit to present at least part of the videodermoscopicanalysis result as modified to the user.
 18. A method for assessment ofhair condition, the method comprising: obtaining a first follicular maprepresenting a first plurality of hair root positions in a firstvideodermoscopy image, obtaining a second follicular map representing asecond plurality of hair root positions in a second videodermoscopyimage, determining a common skin area from the first follicular map andthe second follicular map, relating hair root positions in the secondfollicular map to hair root positions of the first follicular map in thecommon skin area to determine a plurality of related hair rootpositions, each related hair root position of a hair root in the secondfollicular map being related to a hair root position in the firstfollicular map of the same hair root; and comparing a change incondition of individual hair between the first and secondvideodermoscopy image to determine the analysis result suitable forassessment of hair condition.
 19. The method of claim 18, the methodfurther comprising: performing an image processing algorithm on a firstvideodermoscopy image to obtain the first follicular map representingthe first plurality of hair root positions in the first videodermoscopyimage.
 20. A non-transitory computer readable storage media havingcomputer-executable instructions configured to, when executed by aprocessor, perform the steps comprising: obtaining a first follicularmap representing a first plurality of hair root positions in a firstvideodermoscopy image, obtaining a second follicular map representing asecond plurality of hair root positions in a second videodermoscopyimage, determining a common skin area from the first follicular map andthe second follicular map, relating hair root positions in the secondfollicular map to hair root positions of the first follicular map in thecommon skin area to determine a plurality of related hair rootpositions, each related hair root position of a hair root in the secondfollicular map being related to a hair root position in the firstfollicular map of the same hair root; and comparing a change incondition of individual hair between the first and secondvideodermoscopy image to determine the analysis result suitable forassessment of hair condition.